Very high speed photon counting detectors are needed for numerous applications in optical communications, imaging LADAR, quantum cryptography, high-energy physics, spectroscopy, quantum computing and the like. Prior art photon detectors, such as a Visible Light Photon Counter (“VLPC”), see U.S. Pat. No. 4,962,304 incorporated by reference herein, and the closely related Solid-State Photomultiplier (“SSPM”), see U.S. Pat. No. 4,586,068 incorporated by reference herein, have high quantum efficiency (“QE”) and low pulse height dispersion, such that these detectors can operate in the “number mode” to determine the number of photons detected at the detector over very short time intervals. These photon counting detectors are distinguishable from prior art detectors containing a photon counting Avalanche Photodiode (“APD”), see H. Dautet, P. Deschamps, B. Dion, A. D. MacGregor, D. MacSween, R. J. McIntyre, C. Trottier, and P. P. Webb, Photon Counting Techniques With Silicon Avalanche Photodiodes, Appl. Opt. 32, 3894 (1993), incorporated by reference herein, which has a lower QE and larger pulse height dispersion relative to that of a VLPC and SSPM. In an APD detector, “Geiger mode” counting operation occurs in that photons incident upon the detector trigger an avalanche current and the avalanche current is measured over a relatively long reset interval, such as 35 ns, to generate a photon count.
In a typical prior art VLPC, the intrinsic absorption of silicon, from which the intrinsic impurity band detector is formed, provides relatively high quantum efficiency for photon counting in the spectral range having wavelengths of about 0.4–1.0 microns. In a typical prior art SSPM, arsenic doping of silicon provides for extrinsic absorption that achieves high quantum efficiency in the infrared spectral range having wavelengths of about 2–28 microns.
Thus, although the VLPC and SSPM devices are high speed photon counting devices, each has low light absorption in the spectral region having wavelengths of about 1–2 microns, which results in low quantum efficiency in such spectral region. Many excellent light sources and desired applications for high speed photon counting, however, exist for the spectral range having wavelengths of about 1–2 microns.
Therefore, a need exists for a high speed photon counting detector for detecting photons in the spectral range having wavelengths of about 1–2 microns.